SAN FRANCISCO  A federal judge blocked a Bush administration plan to allow commercial logging in Giant Sequoia National Monument, home to two-thirds of the world's largest trees.

U.S. District Judge Charles R. Breyer sided Tuesday with California Attorney General Bill Lockyer and environmental groups that sued the U.S. Forest Service over plans to permit timber cuts on up to 3,200 acres (1,300 hectares) each year in the 328,000-acre (132,700-hectare) preserve, home to 38 Sequoia groves in Central California.

In lawsuits filed last year, Lockyer and conservation groups said the agency's plan, issued in January 2004, violated the proclamation signed by President Bill Clinton in 2000 that established the national monument to protect Sequoias, which can grow up to 270 feet (82.3 meters) tall and 30 feet (9 meters) in diameter.

The plaintiffs argued the plan failed to consider its environmental impacts as required by the National Environmental Policy Act, calling it as a scientifically suspect strategy meant to satisfy the timber industry under the guise of wildfire prevention.

The plan would have allowed up to 7.5 million board feet of timber -- enough to fill 1,500 logging trucks -- to be removed each year from the monument in Sierra Nevada, the plaintiffs said.

In September last year, Breyer issued a preliminary injunction to halt logging in the national monument that began two months earlier. Tuesday's ruling makes the injunction permanent and forces the Forest Service to develop a new management plan.

"We think today's ruling is a huge step toward more intelligent, more protective management of the monument," said Pat Gallagher, the Sierra Club's director of environmental law. "It deserves to be managed like the national treasure that it is."

The conservation groups urged the Bush administration to restore and protect the monument, carved out of the 1.1 million-acre ( 440,000-hectare) Sequoia National Forest, to the same standard as neighboring Sequoia National Park.

"We simply cannot afford to sacrifice for short-term gain majestic Sequoias that have stood for centuries," Lockyer said in a statement. "Today's ruling helps ensure these state gems will be standing for generations to come."

The Forest Service was "very disappointed" in Breyer's ruling and would talk to Justice Department attorneys to determine its next move, which could include appealing the ruling to the 9th U.S. Circuit Court of Appeals, said spokesman Matt Mathes.

The plan to allow logging of trees up to 30 inches (76.2 centimeters) in diameter was aimed at protecting the Sequoia trees from wildfire, Mathes said. He stressed that the Forest Service had no plans to allow logging of giant Sequoias.

Over the years, fire suppression efforts had allowed the Sequoia forests to become overgrown with smaller trees that can catch fire and put the giant trees at risk, Mathes said.

"When the smaller diameter trees catch fire, that's the one thing that can kill the giant Sequoia trees towering above them," Mathes said. "We need to take another look at how we're going to manage this monument to protect these magnificent trees from fire."